Self-locking adjustable device



Oct. 10, 1944. Q HULL SELF-LOCKING ADJUSTABLE DEVICE Filed 001;. 5,'1942 Patented Oct. 10, 1944 SELF-LOCKING ADJUSTABLE DEVICE Charles J.Hull, Buffalo, N. Y., assignor to The Rudolph Wurlitzer Company,

North Tonawanda, N. Y., a corporation of Ohio Application October 5,1942, Serial No. 460,921

1 Claim.

This invention relates generally to adjustable devices but moreparticularly to a self-locking adjustable device for the controls ofelectrical and other equipment installed, for example, on vehicles,ships, airplanes, etc.

One of its objects is to provide an adjustable device of this characterwhich is so designed and constructed as to effectually and positivelyremain in a given position of adjustment even when subjected to severeshocks, jarrings or vibrations of the vehicle on which it is mounted.

Another object of the invention is to provide a self-locking adjustabledevice for electrical and like instruments which is simple, compact andinexpensive in construction, whose parts are so organized and arrangedas to constantly seek and be maintained in a set position, and whichrequires the use of a separate tool to make adjustments.

Other features of the invention reside in the construction andarrangement of parts hereinafter described and particularly pointed outin the appended claim.

In the accompanying drawing:

Figure 1 is a perspective view of the adjustable control embodying myinvention. Figure 2 is an enlarged longitudinal section thereof. Figures3 and 4 are cross sections taken on the correspondingly numbered linesin Figure 2.

Similar characters of reference indicate corresponding parts throughoutthe several views.

While my invention is applicable to various appliances andinstrumentalities requiring adjustment for one purpose or another, ithas been shown, by way of example, in connection with a volume controlfor sound equipment, the numeral 10 indicating the control-housing, Hthe terminals for the electrical connections and I2 the control shaft onwhich the control elements (not shown) of the device are mounted forrotation to different positions of adjustment.

This shaft extends outwardly through a bushing I3 disposed centrally ofthe housing and on its front or exposed end has an externallythreadedportion M to which a tubular member or cap I5 is connected. The outerend of'the control shaft terminates within the inner end of this cap ina head It having a radial coupling pin l1 thereon engaging companionnotches I8 formed in the diametrically opposite sides of the opposinginner end of a hollow actuating stem 19 supported in the cap in axialrelation with said shaft, so that when the stem is turned in onedirection or the other the control shaft is likewise turned to a givenadjusted position. The shaft 12 has a thrust shoulder 20 inwardly of itscoupling head and interposed between the same and the opposing outer endof the bushing I3 is a washer 2|. The coupling notches l8 are of a depthto permit an axial, coupled displacement of the actuating stem relativeto the control shaft for adjustment purposes.

Adjacent its outer end the cap l5 has an outwardly-tapering bore portion22, while the companion end of the shaft-actuating stem l9 has a liketapered portion or shank 23. A coil spring 24 is fitted in this hollowstem, bearing at one end against the closed end of the latter and at itsother end against the shaft-head l 6, and serving constantly to urge thestem into firm wedging engagement with the tapered bore of th cap. Atits outer end the stem is provided with a notch or kerf 25 for receivinga screw driver to turn the stem and the shaft in one direction or the.other to make the adjustments desired. The.

outer end of the cap may be provided with a rim 26 to serve as aprotective guard or sheath for the notched end of the stem.

While manifestly simple and compact in construction, this self-lockingadjustable device is reliable and positive in retaining adjustments andis not liable to be disturbed or dislodged out of adjustment bysurrounding shocks or jarrings. When it is desired to make anadjustment, a screw driver is inserted in the notched end of theactuating stem l9 and, while pressing such stem inwardly against thetension of the spring 24 to break the gripping, tapered joint betweenthe stem and the cap I5, the screw driver is turned in one direction orthe other to set the instrument under control to the position desired.When the proper adjustment is reached, the pressure against the screwdriver is released and the spring 24 urges the stem outwardly in firmgripping contact with the tapered portion 22 of the cap and maintainsthe adjustment positively in position.

I claim as my invention:

In a self-locking device for volume controls, a housing for thecontrollable part thereof having an adjustable control shaft projectingtherefrom and terminating at its outer end in a coupling head,.a tubularcap detachably mounted on said housing in axial relation to said shaftand projecting outwardly beyond the coupling head thereof, said capbeing provided adjacent its outer end with an outwardly tapering boreand terminating outwardl of said bore in a protective rim, a hollowactuating stem closed at its outer end and open at its inner end androtatably supported in said cap in alining relation to said shaft foraxial displacement relative to such parts and having complementarycoupling means at its inner end for detachable driving engagement withthe coupling head of said shaft and having means at its outer endexposed endwise through said cap for receiving a tool to actuate saidstem to adjust the shaft, the exposed end of the stem being sheathed bysaid cap-rim, said stem having an outwardly tapering portion com- 10plementary to the tapering bore of the cap, and a spring fitted in saidhollow stem and hearing at one end against the closed end of the latterand at its opposite end against said shaft-head and normally serving tourge the stem into firm wedging engagement with the cap-bore to retainthe control shaft in its adjusted position when subjected to severeexternal shocks and vibrations,

CHARLES J. HULL.

